In recent years, light-sensitive silver halide photographic materials are required to have higher-level photographic performances such as a higher speed, a better graininess, a higher sharpness and a higher covering power. To cope with such requirements, for example, a variety of complicated technical means as exemplified by the controlling of crystal habits of silver halide crystals per se, grain size distribution, or iodine concentration distribution in each grain have been studied and put into practical use.
In particular, in light-sensitive silver halide photographic materials for medical use, the sharpness of images obtained after development is considered very important since it is necessary to accurately find out a minute nidus to make a diagnosis on a higher level. For example, Japanese Patent Publications Open to Public Inspection hereinafter referred to as "Japanese Patent O.P.I. Publication(s)") No. 28827/1975, No. 185038/1982, No. 158430/1989, etc. disclose that a water-soluble dye is incorporated into a photosensitive layer and/or a layer or layers adjacent thereto so that the sharpness can be improved. Such conventional methods, however, are disadvantageous in that they can not achieve the speed and sharpness at the same time, where an improvement in sharpness results in a decrease in speed. Thus, it has been strongly sought to develop a technique by which the sharpness can be increased without a decrease in speed so that an improved diagnosis can be made.
As a means for improving the processing performance of light-sensitive materials, it is commonly considered effective, for example, to increase the proportion of silver quantity by decreasing the amounts of gelatin or synthetic polymeric compounds used as a binder of silver halide grains, or decrease the amount of a hardening agent.
These methods, however, are accompanied with the disadvantages that they may cause a poor photographic performance such as an increase in fog or a deterioration of graininess and sharpness, and may make poor the physical properties of light-sensitive silver halide photographic materials, as exemplified by scratch resistance, peel-off resistance and pressure resistance. Hence, they can not be said to be preferable methods.
Under such circumstances, it has been strongly sought to provide a light-sensitive silver halide photographic material having an improved speed, sharpness and fixing performance in rapid processing, and also having less development temperature dependence.